Background/Purpose: Clinical response to Mycophenolic acid (MPA) is highly heterogeneous; thus, therapeutic drug monitoring (TDM) of MPA could help improve treatment efficacy. Our objective in this systematic review and meta-analysis was to examine therapeutic ranges for MPA levels that are associated with better outcomes and safety in patients with SLE, particularly those with extra-renal SLE manifestations.

Methods: We performed a comprehensive search of studies measuring an association between MPA levels and clinical SLE response. Using forest plots, we calculated pooled odds of clinical response by MPA levels. Additionally, we measured the weighted mean difference in MPA levels across clinical outcomes. Analysis was performed in all patients with SLE, then separately in patients with extra-renal SLE manifestations.

Results: Among 459 reviewed abstracts, 24 met inclusion. Summarized evidence supported maintaining MPA AUC0-12 levels within 30-60 mg h/L or MPA C12 within 1-2.5 mg/L; these levels were not associated with higher adverse events. Therapeutic MPA levels were associated with 12-fold higher odds (95% CI 5.44-27.35, P < 0.0001, I2 = 41%) of overall clinical SLE response, and 15-fold higher odds (95% CI 4.74–46.89); p < 0.0001; I2=61%) of clinical response in patients with extra-renal manifestations. Additionally, MPA levels were 32 units higher (95% CIs 17.35 45.67) in overall SLE responders, and 39 units (95% CI 15.05-62.53) higher in patients with extra-renal manifestations.

Conclusion: This study highlights the clinical utility of TDM to guide precise MPA dosing to balance efficacy vs. safety in all patients with SLE, including those with extra-renal manifestations.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-significance-of-therapeutic-drug-level-monitoring-for-mycophenolate-in-patients-with-extra-renal-systemic-lupus-erythematosus-a-systematic-review-meta-analysis/